1. Field of the Invention
The present invention refers to a device for adjusting the locking point of an electrode through an electrode-holding vice of an electric arc smelting furnace.
2. Description of the Related Art
Smelting furnaces, generally used in the steel sector, make use of the heat released by electric arcs created through graphite electrodes in order to work.
These electrodes, which are of substantial size, possibly even having a diameter of 800 mm and a length of over 10 m, are supported by vices that are the end part of long steel and copper arms, through which the current necessary for creating the aforementioned electric arcs passes. Such arms stay outside the furnace. Only the part of electrode situated below the vice enters into the furnace.
During operation the electrodes wear down in the bottom part where the arc sparks, and therefore they become gradually shorter. The arc must however always stay in the bottom area of the furnace, in other words where the steel to be poured is located, for which reason the arms go down as low as the cover of the furnace will allow, after which it is necessary to intervene to adjust the relative position between arm and electrode. This normally occurs, after stopping the furnace from operating, through the bridge crane that, in different ways, hooks and holds the electrode while the vice is opened, moved vertically and closed again higher up.
This system, which is currently used in almost all steelworks, has some substantial drawbacks.
In order to carry out the operation it is necessary to stop the furnace for the entire duration of the operation itself, in other words for 2-5 minutes, which, for a modern steelworks, represents a very long time and therefore a very high cost.
The overwhelming majority of steelworks uses the hook of the crane directly to take hold of the electrode. Such a hook, in order to be able to hook onto and unhook from the ring of the nipple located on the top part of the electrode, must be without the obligatory safety device.
The crane in a steelworks is an extremely valuable piece of machinery, which should always be available for emergencies.